Asbestos exposure during uncontrolled removal of sprayed-on asbestos

Our plain-English summary of Asbestos exposure during uncontrolled removal of sprayed-on asbestos, by P. Dumortier, P. De Vuyst (The Annals of Occupational Hygiene, 2012).

The study

• Authors: P. Dumortier, P. De Vuyst
• Journal: The Annals of Occupational Hygiene
• Published: 2012;56(1):49-54
• Type of article: Case report
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos-containing materials in place in buildings, especially sprayed-on asbestos, are still an important health threat. Clearance of these materials has to be operated by specifically trained workers wearing specific individual protection suits after containment of the contaminated area. Good work practices are, however, not always applied. We report the case of two workers hired for ∼1 week to remove sprayed-on amosite asbestos during the remodeling of a former industrial hall. Regulatory protective equipments were not used. A legal action was initiated after disclosure of the working conditions. Medical examinations were performed 18 and 22 months after exposure. Workers denied any other asbestos exposure. Lung function tests and chest computed tomography scans were normal. Very high levels of asbestos fibers and bodies were discovered on mineralogical analysis of bronchoalveolar lavage fluid (BALF) by phase contrast light microscopy and analytical electron microscopy. All fibers were amosite. An extrapolation considering duration of exposure, breathing pattern, and BALF fiber content suggests that the workers were exposed to airborne fiber concentrations in the range from several tens to about a hundred World Health Organization fibers per milliliter air. In conclusion, exposures to historical airborne fiber levels prevailing half a century ago may still occur today when the work regulations are not applied. In these conditions, even very short exposures may result in considerable lung fiber retention in case of amphibole exposure with the subsequent risk for developing asbestos-related diseases. Fiber analysis in BALF is useful to clarify such exposures.

In plain English

This case report described two of nine workers who removed sprayed-on asbestos containing 90% amosite during remodeling of a former industrial hall. The team hand-scraped 4000 kg in one week without wetting, with no protection the first day and only simple facial masks afterward. Only two could be traced after a legal action began. Their estimated exposures were 40 and 16 hours; they were examined 18 and 22 months later. Lung function tests and chest CT scans were normal. Their bronchoalveolar lavage (lung-washing) fluid held 349 and 50 asbestos bodies per milliliter, versus under 1 expected in people of the general population without obvious asbestos exposure, and all fibers analyzed by electron microscopy were amosite. By extrapolation, the authors estimated airborne levels of 86 and 57 WHO fibers per milliliter of air, while noting its inputs vary widely; the Belgian workplace limit is 0.1 fibers per milliliter. The authors concluded that exposures like those of half a century ago can still occur when regulations are ignored and that resulting diseases should be expected, although individual risk cannot be predicted.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Case report of two workers, with mineral fiber analysis of bronchoalveolar lavage fluid and a calculated estimate of the airborne fiber levels they breathed
• Who was studied: Two workers, aged 33 (case 1) and 34 (case 2) at the time of exposure, the only two who could be traced from a team of nine foreign workers. They were unskilled construction workers and building painters with no suspected other asbestos exposure.
• Exposure: Uncontrolled hand-scraping removal of sprayed-on asbestos containing 90% amosite (4000 kg removed in 1 week). There was no preliminary wetting and no proper collective or personal protection: no protection on the first day, then only simple facial masks. No air depressurization was used and no airborne fiber measurements were taken.
• Main results:
  • Estimated exposure duration was 40 h for case 1 and 16 h for case 2. Bronchoalveolar lavage was done 18 months (case 1) and 22 months (case 2) after exposure.
  • Lung function tests and chest computed tomography scans were normal in both workers.
  • Asbestos bodies per milliliter of lavage fluid (light microscopy): 349 in case 1 and 50 in case 2. The reference values given for people of the general population without obvious asbestos exposure were under 1 asbestos body per milliliter and under 300 fibers longer than 1 micrometer per milliliter.
  • Concentrations of asbestos fibers and bodies in lavage fluid were described as extremely elevated compared with reference values for people of the general population without obvious asbestos exposure.
  • Total fibers per milliliter of lavage fluid (analytical electron microscopy): 22 542 in case 1 and 3648 in case 2.
  • WHO fibers (longer than 5 micrometers, thinner than 3 micrometers, thicker than 0.2 micrometers) per milliliter of lavage fluid: 12 210 in case 1 and 2450 in case 2.
  • All fibers analyzed and sized by transmission electron microscopy were amosite. Fiber size distributions did not differ significantly between the two cases.
  • Most structures counted as asbestos bodies had an atypical appearance, with a very thin, often partial coating.
  • Extrapolated airborne fiber concentrations were 86 WHO fibers per milliliter of air (case 1) and 57 (case 2).
  • The authors stated that these estimated levels considerably exceed the current Belgian workplace limit of 0.1 fibers per milliliter of air.
• The authors' conclusion: The authors concluded that exposures to the airborne fiber levels of half a century ago may still occur today, even in countries with stringent asbestos laws, when work regulations are not respected, and that diseases resulting from such exposures should be expected in the future.
• Limitations the authors state:
  • The airborne concentrations are rough extrapolations. The values entered for the calculation (lavage-to-lung-tissue ratio, dry-to-wet tissue ratio, breathing volume, deposition efficiency) vary and can significantly change the result. Lung clearance between exposure and lavage was neglected.
  • No airborne fiber measurements were made during the work.
  • Only two of the nine workers could be traced, and information about exposure conditions had to be collected retrospectively.
  • The time since exposure was too short for lung or pleural lesions to have developed.
  • Future risk for a given fiber dose cannot be predicted for an individual. An elevated lung asbestos burden proves exposure but is neither a sign nor a predictor of disease.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Amosite.

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Asbestos-Containing Material (ACM), Amosite, Bronchoalveolar Lavage (BAL), Amphibole Group.

Related studies

• Worker exposure to asbestos during removal of sprayed material and renovation activity in buildings containing sprayed material — N.W. Paik, R.J. Walcott, et al. (1983)
• Personal and static sample measurements of asbestos fibres during two abatement projects — A. Dufresne, C. Dion, et al. (2009)
• Exposure to airborne asbestos during abatement of ceiling material, window caulking, floor tile, and roofing material — J.H. Lange, S.L. Sites, et al. (2006)
• Asbestos abatement in a location previously improperly abated — J.H. Lange, S.L. Sites, et al. (2006)
• A technical comparison of evaluating asbestos concentration by phase-contrast microscopy (PCM), scanning electron microscopy (SEM), and analytical transmission electron microscopy (ATEM) as illustrated from data generated from a case report — R.F. Dodson, S.P. Hammar, et al. (2008)
• Instances of sprayed asbestos use in Brazil — G. Tweedale (1998)

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